1. Field of the Invention
The present invention relates to an image processing circuit which performs a filter process. In addition, the present invention relates to a display device including the image processing circuit. Further, the present invention relates to an electronic device including the display device in a display portion.
2. Description of the Related Art
The quality of display images, for example, of display devices such as liquid crystal display devices (also referred to as LCDs) and EL display devices (also referred to as electroluminescent display devices) can be improved by image processing.
As an example of the image processing, a filter process (also referred to as filtering) which is also performed in devices such as scanners and printers can be given. The filter process is an arithmetic process which weights each pixel data value by using a matrix of a weighting coefficient called a filter and calculates the sum of the pixel data values. By the filter process, processing such as image averaging, image enhancement, edge detection, or detection of a certain pattern can be performed.
As an example of a device having an image processing function including the filter process (such a device is also referred to as an image processing circuit or an image processing device), Patent Document 1 can be given.
An image processing device (image processing circuit) disclosed in Patent Document 1 performs an edge detection process and a filter process by using a plurality of line memories connected to each other in series.
The line memory is a memory which can store pixel data corresponding to pixels in one row.